To destroy or inactivate harmful microorganisms in different types of fluids are today common in most application areas. For example, most liquid foodstuffs are exposed to one or more process steps that are designed to destroy unwanted microorganisms and thus extend the shelf life of the product. Similarly, different processes are used for purifying different kinds of contaminated water alternatively sludge, petroleum products or other pumpable products.
A common method for food treatment is so-called pasteurization. During pasteurization the food in question is heated for a short period of time to a temperature which is high enough to inactivate the microorganisms that possibly are present in the food. When the food is heated during pasteurization, however, its taste and chemical composition may change due to the increase in temperature.
Another disadvantage with pasteurization is that a large amount of energy is needed to heat the food, and then cooling it to a suitable storage temperature. Energy consumption is currently related to high costs that ultimately results in an increase in the cost of the processed food.
In the case where different kind of water is purified to achieve a higher water quality several treatment methods are used, this includes treatment with chemicals, biological methods, UV light or ozone gas. These methods are however, costly and often require the use of additional methods to achieve the desired end-result.
Another option to deactivate microorganisms in fluids is to expose the liquid in case to an electric field.
A known method is based on a tube which has been provided with electrodes, between which an electrical voltage is applied. When a liquid or similar flows passing the electrodes, the liquid will be subjected to an electric field. In this case, however, it is difficult to control the extent of the treatment, this since the electric field the field strength is difficult to predict. Furthermore, the liquid flow velocity will differ at different location over the intersection of the tube, leading to an uneven treatment.
SE-520 666 C2 describes a method and an arrangement where a pumpable substance is exposed to an electric field. When the method is performed, the pumpable substance is first brought into the electric field, after which it is exposed to the electric field. Finally the pumpable substance is brought out from the electric field. While the substance is exposed to the electric field, at least one volume is separated which is moved during the exposure to the electric field. The above arrangement for the treatment of a pumpable substance using an electric field includes a container in which the pump only substance can be accommodated. The arrangement also includes a source for the generation of the electric field, and at least a separated space in which the pumpable can be accommodated and subjected to the electric field. When the above method and arrangement is used a significant risk that the previously treated pumpable substance is contaminated in case something fails. This risk exists because no measurement is performed where the actual electric field is ensured during the exposure. Would therefore not properly treated pumpable substance be carried forward after treatment, then the previously treated substance is contaminated. Furthermore, there are no organs to ensure that no air or gas bubbles are present in the substance being treated or that the substance can be pressurized to minimize the risk of air-filled cavities in the treated substance.